The invention relates to pressure-sensitive adhesive products having a breathable backing particularly for adhering to skin or like surfaces.
Pressure-sensitive adhesive tapes and the like are used in a wide variety of applications where there is a need for a breathable backing. These tapes generally are designed to adhere to a surface that is a source of moisture such as skin; however, porous articles can be a moisture source if they are in communication with a fluid source. Tapes designed to adhere to skin include, for example, medical tapes such as wound or surgical dressings, athletic tapes, surgical drapes, or tapes or tabs used in adhering medical devices such as sensors, electrodes, ostomy appliances or the like. Lack of breathability with these tape products can result in overhydration and sometimes maceration of the skin. For example, U.S. Pat. No. 5,614,310 suggests using a backing having moisture vapor transmission rate (MVTR) value of at least 500 g/m.sup.2 /day (measured using ASTM E 96-80 at 40.degree. C.).
A discontinuous adhesive coating on a breathable backing allows the skin to breathe, at least in the areas of the backing not coated with adhesive. This approach is disclosed in U.S. Pat Nos. 4,595,001 Cotter); U.S. Pat. No. 5,613,942; EP 353972; and EP 91800. These patent documents generally teach intermittent coating of adhesives onto different backings. For example, U.S. Pat No. 5,613,942 describes printing pressure-sensitive adhesives using a release coated calender roll process similar to Gravure printing. This patent also teaches screen-printing. However, pattern coating or printing of adhesives in this manner is problematic as it generally requires solvents, which are environmentally problematic, It would be preferred from environmental, manufacturing (e.g. elimination of the need for expensive solvent recovery) and performance perspectives to have adhesives coatable directly from a melt phase.
With polyolefin type tape backings and like low energy materials there is often a need to increase the surface energy of the backing material to allow the pressure-sensitive adhesive to remain securely bonded to the backing. This is generally termed priming and can be done with surface treatments such as flame treatments, corona treatment or like oxidizing surface treatments. These are generally acceptable but require a separate process step complicating manufacture of the tape product. It is also known to apply primer coatings to a surface of the backing. These often are curable coatings as are disclosed in U.S. Pat. Nos. 5,639,546; 5,631,079; and 5,503,927. Although effective, they require one or more further process steps and can occlude the pores of a porous backing. Melt additives and tie layers are also often used with film backings, which eliminate the need for a separate priming step however these films are generally not porous. The invention is directed at providing a pressure-sensitive adhesive tape backing product that is simple to manufacture, does require a separate priming step, and also is extremely breathable.